> [TELECOM Digest Editor's Note: Many of the older 6 button/5 line> phones had a small 'buzzer' inside them also and the incoming ringing> voltage rang *one* of the phones; the other phones in the group> would 'buzz'. Also sometimes one of the line appearances was a dial> intercom to call the other phones in the group; the phones, on an> intercom call would 'buzz' with a certain cadence rather than 'ring'> (with a certain cadence) as they did for outside calls. PAT]

That sounds right, although a motor-generator to drive a buzzer sounds
pretty Rube Goldberg. A DC buzzer is a pretty simple device.